Han Do Lee

Severe and extensive traumatic axonal injury following minor and indirect head trauma

ABSTRACT Objectives: This study reports on a patient with mild traumatic brain injury (TBI) who showed severe and extensive traumatic axonal injury (TAI) of various neural tracts following minor and indirect head trauma, which was demonstrated by diffusion tensor tractography (DTT). Case description: A 26-year-old female patient suffered from indirect head trauma resulting from flexion-hyperextension injury after being hit from behind by a slowly moving car. At the time of head trauma, she felt tingling sensation on her four extremities; however, she did not experience loss of consciousness. At 5-day after onset, she began to experience tremor on the right leg and, subsequently, tremor had also developed in the left leg. At 8-days after onset, she could not even stand due to tremor of both legs and began to feel a tingling sensation on both legs. Since ~ 2 weeks after head trauma, myoclonus had developed mainly in the trunk. After 10-weeks after head trauma, when she started rehabilitation, she showed mild quadriparesis (4+/4+) with severe weakness of the proximal joint (shoulder/hip, 4–/4–), severe resting and intentional tremor, ataxic gait and severe myoclonus. Conclusions: Severe and extensive TAI of various neural tracts was demonstrated in a patient with mild TBI following minor and indirect head trauma, using DTT.

Injury of the Mammillothalamic Tract in Patients with Thalamic Hemorrhage

Objective: Injury of the mammillothalamic tract (MTT) has been suggested as one of the plausible pathogenic mechanisms of memory impairment in patients with thalamic hemorrhage; however, it has not been clearly demonstrated so far. We attempted to investigate whether injury of the MTT documented by diffusion tensor tractography following thalamic hemorrhage correlates with cognitive impairment. Methods: We recruited 22 patients with a thalamic hemorrhage and 20 control subjects. MTTs were reconstructed using the probabilistic tractography method. Patients were classified into two subgroups: reconstructed group, patients whose MTT was reconstructed in the affected hemisphere, and non-reconstructed group, patients whose MTT was not reconstructed. Results: Mammillothalamic tract was reconstructed in 5 (22.7%, reconstructed group) patients in the affected hemisphere and was not reconstructed in the remaining 17 patients (77.3%, non-reconstructed group). In addition, the MTT was not reconstructed even in the unaffected hemisphere in four patients (23.5%) in non-reconstructed group. Fractional anisotropy and mean diffusivity values of the affected hemisphere in reconstructed group also did not show significant differences from those in the unaffected hemisphere of reconstructed group and the control group (p > 0.05). However, the tract volume of the affected hemisphere in reconstructed group was significantly lower than that of the unaffected hemisphere in reconstructed group and the control group (p < 0.05). Conclusion: A large portion of patients with thalamic hemorrhage appeared to suffer severe injury of the ipsilesional MTT (77.3%) and 18.2% of them appeared to suffer severe injury even in the contralesional MTT. In addition, the remaining 22.7% of patients who had preserved integrity of the ipsilesional MTT appeared to suffer partial injury of the ipsilesional MTT.

Changes of the corticospinal tract in the unaffected hemisphere in stroke patients: A diffusion tensor imaging study

Abstract We investigated changes of the corticospinal tract (CST) in the unaffected hemisphere according to severity of the CST injury, using diffusion tensor imaging (DTI). According to the severity of the CST injury in the affected hemisphere, the stroke patients showed different aspects of fiber volume increment of the CST in the unaffected hemisphere; the fiber volume was increased in the early phase in patients with mild injury of CST and later phase in patients with severe injury of CST.

Recovery of Hypersomnia Concurrent With Recovery of an Injured Ascending Reticular Activating System in a Stroke Patient: A Case Report.

AbstractWe report on a stroke patient who showed recovery of hypersomnia concurrent with the recovery of an injured ascending reticular activating system (ARAS), which was demonstrated by diffusion tensor tractography (DTT).A 70-year-old female patient underwent coiling of the left ruptured posterior communicating artery after subarachnoid hemorrhage and both extraventricular drainage for management of an intraventricular hemorrhage. At 2 months after onset, when she started rehabilitation, she exhibited intact consciousness, with the full score on the Glasgow Coma Scale: 15. However, she showed severe hypersomnia: she always fell asleep without external stimulation and the Epworth Sleepiness Scale (EPS) score was 24 (full score: 24, cut off for hypersomnia: 10). She underwent comprehensive rehabilitative therapy, including neurotropic drugs, physical therapy, and occupational therapy. Her hypersomnia has shown improvement as 14 (3 months after onset), 11 (4 months after onset), 7 (12 months after onset), and 6 (24 months after onset), respectively.On 2-month DTT, narrowing of both lower dorsal and ventral ARASs was observed on both sides: in particular, among 4 neural tracts of the lower ARAS, the right lower ventral ARAS was the narrowest. By contrast, on 24-month DTT, the 4 narrowed neural tracts of both lower dorsal and ventral ARASs were thickened compared with those of 2-month DTT.Recovery of hypersomnia with recovery of an injured lower ARAS on DTT was observed in a stroke patient. Our results suggest that evaluation of the lower ARAS using DTT might be useful for stroke patients with hypersomnia.

Injury of the cingulum in patients with putaminal hemorrhage: a diffusion tensor tractography study

Objectives: Little is known about the pathophysiological mechanisms of cognitive impairment in patients with putaminal hemorrhage (PH). Using diffusion tensor tractography, we investigated injury of the cingulum in patients with PH. Methods: We recruited 63 patients with PH, who were classified according to three groups, based on integrity of the cingulum to the lower portion of the genu of the corpus callosum: group A; preserved integrity, group B; discontinuation of integrity in the affected hemisphere, and group C; discontinuation of integrity in both hemispheres. Results: Thirty four patients (54.0%) belonged to group A, 16 patients (25.4%) to group B, and the remaining 13 patients (20.6%) to group C. Regarding the Mini-Mental State Examination, significant differences were observed between group A and group C, and between group B and group C without significant difference between group A and group B (p < 0.05). In terms of the volume of hematoma, significant differences were observed among the three groups (p < 0.05). Regarding the most anterior point of the hematoma, significant differences were observed between group A and groups B and C (p < 0.05); in contrast, regarding the most point of hematoma, significant differences were observed between group C and groups A and B, respectively (p < 0.05). Conclusion: We found that the anterior cingulum is vulnerable to PH. Therefore, our results suggest the necessity for evaluation of the cingulum in patients with PH particularly if the hematoma is large or close to the anterior margin or midline of the brain.

Limb-Kinetic Apraxia Due to Injury of the Corticofugal Tract from the Secondary Motor Area in a Stroke Patient.

A 52-year-old right-handed male patient presented with complete weakness of the left extremities at the onset of hemorrhagic transformation after right middle cerebral artery territory infarct. When he started rehabilitation at 2 weeks after onset, he exhibited severe left hemiparesis with completeweakness of the left finger flexor and extensor (manual muscle test result, 0/0). The patient_s scores on the Mini-Mental State Examination and the ideomotor apraxia test were 28 (cutoff score, G25) and 40 (cutoff score, G32), respectively. The patient underwent a comprehensive rehabilitative management program, including movement therapy and neurotrophic drugs (ropinirole, 3 mg; amantadine, 300 mg; and levodopa, 500mg). During a 2-week period of intensive rehabilitation, the patient showed significant motor recovery in the left extremities to the extent of a nearly normal state including finger flexor and extensor (manual muscle test result: 4/4). A 6-channel head coil on a 1.5-T Philips Gyroscan Intera was used for acquisition of diffusion tensor imaging data at 2 weeks after onset. For reconstruction of the corticospinal tract (CST), the upper pons and mid pons on the color map. For reconstruction of the corticofugal tracts (CFTs) from the premotor cortex (PMC) and supplementary motor area (SMA). The integrities of the CST, the CFT from the PMC, and the CFT from the SMA were preserved in both hemispheres (Fig. 1). However, the CST, the CFT from the PMC, and the CFT from the SMA were thinner than those of the left side, respectively. We think that the motor weakness of the left extremities observed in this patient was mainly ascribed to

New Neural Tracts from Bilateral Fornical Columns to Compensate Bilateral Injury of Fornical Crura.

From the Departments of Physical Medicine and Rehabilitation (SHJ, HDL) and Neurosurgery (SHK), College of Medicine, Yeungnam University, Taegu, Republic of Korea. This work was supported by the National Research Foundation (NRF) of Korea Grant funded by the Korean Government (MSIP) (2015R1A2A2A01004073). Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.

Impaired consciousness caused by injury of the lower ascending reticular activating system: evaluation by diffusion tensor tractography.

A 34-year-old male patient underwent conservative management for traumatic hemorrhage in the right frontal lobe (Figure 1A). The patient lost consciousness for approximately 4 weeks and experienced post-traumatic amnesia continuously from the time of the accident. The patients Glasgow Coma Scale score (Teasdale et al., 1974) was 6 when he arrived at the hospital. At 5 weeks after onset, he was transferred to the rehabilitation department to undergo rehabilitation. Brain MRI showed malactic lesions in both the frontal lobes and right thalamus (Figure 1B). The patient exhibited impaired consciousness, with a Glasgow Coma Scale score of 9 and Coma Recovery Scale-Revised score of 8 (Giacino et al., 2004). Figure 1 Brain CT images, magnetic resonance images and diffusion tensor tractography (DTT) images of a 34-year-old male patient with traumatic brain injury. Diffusion tensor tractography (DTT) data were obtained at 6 weeks after onset using a 6-channel head coil on a 1.5 T Philips Gyroscan Intera (Philips, Best, the Netherlands) with single-shot echo-planar imaging. Imaging parameters were as follows: acquisition matrix = 96 × 96; reconstructed matrix = 192 × 192; field of view = 240 × 240 mm2; repetition time = 10,726 ms; echo time = 76 ms; parallel imaging reduction factor (SENSE factor) = 2; EPI factor = 49; b = 1,000 s/mm2; number of excitations = 1; and a slice thickness of 2.5 mm. FACT algorithm was used for fiber tracking. For ascending reticular activating system (ARAS) analysis, the seed region of interest (ROI) was given on the pontine reticular formation. According to previous reports (Yeo et al., 2013; Jang et al., 2014), the target ROI was placed on the thalamic intralaminar nuclei to analyze the connectivity of the intralaminar nuclei. The patient showed intact neural connectivity between the thalamic intralaminar nuclei the frontal lobe. However, the left lower ARAS between pontine reticular formation and thalamic intralaminar nuclei was thinner than the right lower one of the same patient and those in five age-matched healthy control subjects (Figure 1C). In this study, we evaluated the ARAS in a patient with severe traumatic brain injury through two portions: First, three-dimensional reconstruction at the lower ARAS between the pontine reticular formation and the thalamic intralaminar nuclei, second, neural connectivity of the upper ARAS between the thalamic intralaminar nuclei and the cerebral cortex. Our results showed that the left lower ARAS was thinner than that of the right side of the patient and those of normal subjects. These findings appear to suggest an injury of the left lower ARAS. This injury was attributed to traumatic axonal injury because the conventional brain MRI of the patient was normal in the left thalamus and brainstem. Before analysis of the ARAS, we assumed that the main lesion would be located in the right ARAS and left upper ARAS because the brain MRI showed malactic lesions in both frontal lobes and the right thalamus. The main lesion site was detected in the left lower ARAS between the thalamic reticular formation and the thalamic intralaminar nuclei (Edlow et al., 2013; Jang et al., 2015a, b). Our results suggest that analysis of the ARAS using DTT would be useful for elucidating the cause of impaired consciousness. However, limitation of DTT with 1.5 T MRI should be considered, because a higher tesla MRI such as 3.0 T, can show better resolution and identify small tract more precisely. This work was supported by the National Research Foundation (NRF) of Korea Grant funded by the Korean Government (MSIP), No. 2015R1A2A2A01004073.

Diffusion tensor tractography studies on mechanisms of recovery of injured fornix

The fornix, which connects the medial temporal lobe and the medial diencephalon, is involved in episodic memory as an important part of the Papez circuit. The mechanisms of recovery of an injured fornix revealed by diffusion tensor tractography in the five studies are summarized as follows: 1) recovery through the nerve tract from an injured fornical crus to the medial temporal lobe via the normal pathway of the fornical crus; 2) recovery through the nerve tract originating from an ipsi-lesional fornical body connected to the ipsi-lesional medial temporal lobe via the splenium of the corpus callosum; 3) recovery through the nerve tract from the ipsi-lesional fornical body extending to the contra-lesional medial temporal lobe via the splenium of the corpus callosum; 4) recovery through the nerve tract originating from the ipsi-lesional fornical column connected to the ipsi-lesional medial temporal lobe; and 5) recovery through the nerve tract originating from the contra-lesional fornical column connected to the ipsi-lesional medial temporal lobe via the contra-lesional medial temporal lobe and the splenium of the corpus callosum. These diffusion tensor tractography studies on mechanisms of recovery of injured fornical crus appeared to provide useful information for clinicians caring for patients with brain injury, however, studies on this topic are still in the beginning stages.

Recovery of akinetic mutism and injured prefronto-caudate tract following shunt operation for hydrocephalus and rehabilitation: A case report

Rationale: A 76-year-old female patient was diagnosed with an aneurysmal subarachnoid hemorrhage following rupture of a right posterior communicating artery aneurysm. Patient concerns: She was treated surgically with clipping of the aneurysmal neck. Six months after onset, when starting rehabilitation at our hospital, she showed no spontaneous movement or speech. Diagnoses: aneurysmal subarachnoid hemorrhage following rupture of a right posterior communicating artery aneurysm. Interventions: During 2 months’ rehabilitation, her AM did not improve significantly. As there was no apparent change, she underwent a ventriculo-peritoneal shunt operation for hydrocephalus 8 months after her stroke. After the surgery, she remained in the AM state, but participated in a comprehensive rehabilitative management program similar to that before shunt operation. During 1 months intensive rehabilitation, her AM gradually improved. At 9 months after onset, she became able to perform some daily activities by herself including eating, washing, and dressing. In addition, she could speak with some fluency. Outcomes: On 6-month DTT, the neural connectivity of the caudate nucleus (CN) to the medial prefrontal cortex (PFC, Broadmann area [BA]: 10 and 12) and orbito-frontal cortex (BA 11 and 13) was low in both hemispheres. However, the neural connectivity of the CN to the medial PFC increased on both sides on 9-month DTT. The integrity of the arcuate fasciculus (AF) was preserved in both hemispheres on both 6- and 9-month DTTs. Lessons: Recovery of AM and injured PCTs was observed in a stroke patient.